@loewian I know, I know. He's sufficiently viewed by people as pre-shulchan arukh (as evidenced by the fact that you are the first person in three years to notice I snuck him in) that I think it's worth bending precision to include him because of how strong a point it is that even he, who wanted to justify the alleged minhag, didn't dare argue on consensus in this regard.
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Double AA♦Dec 10 '14 at 23:11

It's a machlokes Tanna'im, Amora'im, Rishonim, Achronim and contemporary poskim. The original machlokes is how to interpret "bchol moshvoseichem" in the Torah. Most of the standard rishonim holds it does apply mdoraysa in chutz l'aretz (Rambam, Rif, Rosh) and this is how the shulchan aruch paskens. Most people have been lenient on this issue for a long time, with various kulos suggested (see Rema, Bach, Taz, Aruch haShulchan).

The prohibition to eat "new" grain (grain which was harvested after the day of the omer offering, which is on Day 2 of Pesach) does apply in the Diaspora, according to most poskim.

However:

Wheat often sits in silos for a year or two after harvesting, before it is made into flour. grains like barley are dried and sealed in plastic bags, and they can sit in a warehouse or on the shelf for years.

The Rema brings a double doubt: maybe the grain product you now possess is old, and even if it was harvested this year, maybe it took root before Pesach.

R' Moshe Feinstein says that one may rely on this Rema, but it is better to be strict, if possible.

Until recently, most kosher consumers in the Diaspora were not able to be strict.

Today, one can obtain a list of barcodes for bags of flour in the supermarket (at least in the United States). Thus, it is possible to find out exactly when any given bag of flour was milled. If it was milled before Pesach of this year, obviously the grain took root before Pesach, and it is yoshon.

Certainy one may rely on the Rema, as cited by R' Moshe Feinstein, and eat in the home of any shomer kashrus, or any reliably certified kosher restaurant, regardless of their zeal with barcode checking on bags of flour and dried barley.

However, the issur of chadash is a Torah prohibition. If one has sufficient storage space at home to purchase all grain products before the first chadash could possibly hit the stores (if memory serves, you have from pesach until at least Rosh Hashannah), that is a praiseworthy practice.

I'm not sure the sefeik sefeika has to do with the question. The Rama agrees that Chadash applies in the Diaspora. Isn't that all the question asked?
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Double AA♦Jan 2 '12 at 14:58

@DoubleAA, well, if the asker was asking on a practical level, then the Rama is relevant.
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msh210♦Jan 2 '12 at 16:24

@msh210 I think the Rama is equally applicable in Israel just like Chu"l. I think that how the issur manifests itself in our daily lives is a different question and very much depends on the practical details of one's location.
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Double AA♦Jan 2 '12 at 16:30

1

@DoubleAA just to say "yes, issur chadash applies in the Diaspora" would not explain why many Orthodox Jews in the Diaspora do not meticulously check every barcode of every bag of flour or grain product during the fall and winter months. I filled in information to bridge the gap between "yes, it applies" and "every grain product you've ever eaten from Sukkos to Pesach is treif"
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user1095Jan 2 '12 at 16:31

@Will I still think that belongs in a separate question. Feel free to ask it and answer it yourself!
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Double AA♦Jan 2 '12 at 16:33